The purpose of this proposal is to obtain funds permitting organization of an ASM Conference on mechanisms of microbial virulence. This is a critical field of microbiology which, under the influence of modern techniques of molecular biology and genetics, is of burgeoning interest to those active in both basic and applied areas of the science. The strategy of the Conference is to first define nonspecific mechanisms of host defense successful in preventing infection by saprophytic microorganisms and then to show how virulence determinants of pathogenic species serve to overcome these nonspecific mechanisms. Emphasis will be placed on providing information at a basic molecular level permitting appreciation of strategies common to extracellular, facultative intracellular, and obligate intracellular parasites. An extra-ordinary group of speakers has agreed to participate at the Conference and full attendance by an audience of working scientists and graduate students is anticipated.